VIC Terrible flat spot 2.0lt T4

[emmdarc]

Hi all,

New to this forum and seeking answers to an inconsistent problem with my T4 transporter 2.0lt AAC engine. I bought this vehicle because it has a wheelchair lift for my 10yo boy. Love the van, but hate the problem I'm having. It's driving me crazy!
Anyway, I'm posting my introduction so I can gain further information from VW gurus in Australia......Thanks Joel

[h100vw]

Welcome to the forum.

Is the flat spot present in all gears or at a particular road speed or engine revs?

I had a 2litre Ibiza GTI which is a broadly similar engine to yours. It would hunt about when you were doing bang on 70, with whiff of throttle. It only did it on the flat. A touch more or less throttle would stop it.

I never bothered looking for it but suspected that the throttle position potentiometer was either worn or had got dirty from been driven with the throttle in the same place for a long time.

Replacement would be the easiest way to confirm my problem, which may be similar to yours.

First off thought you should have the ECU checked for fault codes and go from there.

If northing else it would be worth making sure that normal service items like fuel filter, air filter, plugs, leads, cap and rotor are in good condition.

Gavin

[emmdarc]

Thanks Gavin,

A lot of the time the van seems to run perfect? Then all of a sudden, I will change down through gears and sometimes it will stall, other times it will just recover and regain normal idle. But then it just doesn't want to go. Seems to be more obvious when cold and changing through gears.
I have tried numerous things:
New plugs
New air filter
New fuel filter
New rotor
New Cap
New small diameter air lines from ecu and air inlet
Tied new after martket throttle position sensor, but made car hunt. Reinstalled original
Tried new aftermarket Idle stabalisation Valve, but also made car hunt. Reinstalled another secondhand unit. No change
New after market coolant sensor. No change
New fuel pump. No change
Have cleaned out the cold start valve. No change
Have changed the fuel pressure regulator with secondhand unit. No change

I am wondering if the thermostat in this thing may be faulty. Never seems to get much above 80 degrees?? Don't know if the temp message to the ecu might be too low??

Also considering changing the coil and or ECU? Are they a common fault.

I did take the van to Volkspower in Melbourne. He said he checked the fault codes, but nothing came up? Don't know if he just wanted to get rid me or not? He said they won't tell you much anyway? Should I take to a genuine dealer?

Any thoughts or ideas are greatly appreciated...Thanks Joel